Potential antidiabetic drugs of metformin with insulin-enhancing anions [VO2(dipic)]- and [VO2(dipic-OH)]-: Synthesis, characterization and X-ray crystal structure

Abstract

Two new complexes of antidiabetic drug metformin, [HMet][VO2(dipic)]·H2O (1) and [HMet][VO2(dipic-OH)]·H2O (2), where H2dipic = 2,6-pyridinedicarboxylic acid, H2dipic-OH = 4-hydroxy-2,6-pyridine dicarboxylic acid and Met = metformin, were synthesized. These complexes were characterized by elemental analysis, 1H and 13C NMR, FTIR, and UV-Vis spectroscopies. Solid-state structures of [HMet][VO2(dipic)]·H2O (monoclinic, P21/n) and [HMet][VO2(dipic-OH)]·H2O (monoclinic, P21/c) were determined by means of single crystal X-ray diffraction analysis. In these complexes, metformin is monoprotonated and acted as counter ion. These compounds are soluble in water and hydrogen bond interactions stabilize their crystal structures.